Hi, Taksashi,
> One thing we can try is a patch like below. But, I'm not sure whether> this is correct over all architectures, too. At best, a generic API> would be helpful for such a thing...> + area->vm_page_prot = pgprot_noncached(area->vm_page_prot);
Well, it's not enough, because the kernel mapping of buffer is stillcached... A hack below does the job, but it is not nice as well...
Cheers
Paweł
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.cindex 59b29cd..304f9e5 100644--- a/sound/core/pcm_native.c+++ b/sound/core/pcm_native.c@@ -3159,6 +3159,9 @@ static struct vm_operations_struct snd_pcm_vm_ops_data = static int snd_pcm_default_mmap(struct snd_pcm_substream *substream, struct vm_area_struct *area) {+#ifdef pgprot_noncached+ area->vm_page_prot = pgprot_noncached(area->vm_page_prot);+#endif area->vm_ops = &snd_pcm_vm_ops_data; area->vm_private_data = substream; area->vm_flags |= VM_RESERVED;diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.cindex 7bd5852..c98a4ec 100644--- a/sound/usb/usbaudio.c+++ b/sound/usb/usbaudio.c@@ -714,7 +714,8 @@ static int snd_pcm_alloc_vmalloc_buffer(struct snd_pcm_substream *subs, size_t s return 0; /* already large enough */ vfree(runtime->dma_area); }- runtime->dma_area = vmalloc(size);+ runtime->dma_area = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM,+ PAGE_KERNEL_NOCACHE); if (! runtime->dma_area) return -ENOMEM; runtime->dma_bytes = size;
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